Redox amplification processes have been described, for example in GB-A-1 268 126, GB-A-1 399 481, GB-A-1 403 418 and GB-A-1 560 572. In such processes color materials are developed to produce a silver image (which may contain only small amounts of silver) and then treated with a redox amplifying solution (or a combined developer-amplifier) to form a dye image.
The developer-amplifier solution contains a reducing agent, for example, a color developing agent, and an oxidizing agent which will oxidize the color developing agent in the presence of the silver image which acts as a catalyst. The photographic material used in such a process may be a conventional coupler-containing silver halide material or an image transfer material containing redox dye releasers.
Oxidized color developer reacts with a color coupler (usually contained in the photographic material) to form image dye. The amount of dye formed depends on the time of treatment or the availability of color coupler rather than the amount of silver in the image as is the case in conventional color development processes.
Examples of suitable oxidizing agents include peroxy compounds including hydrogen peroxide and compounds which provide hydrogen peroxide, e.g. addition compounds of hydrogen peroxide; cobalt (III) complexes including cobalt hexammine complexes; and periodares. Mixtures of such compounds can also be used.
A particular application of this technology is in the processing of silver chloride color paper, especially such paper with low silver levels.
However, as the chemistry used in redox amplification processes are inherently unstable, it is uneconomic to use large volumes of processing solutions.
WO-A-91/12567 discloses a method for processing photographic material using a redox amplification process using the minimum of processing solution whilst providing fully acceptable results. The photographic material is passed through a tank containing the unstable processing solution and the processing solution is circulated through the tank at a rate in the range of 0.1 to 10 tank volumes per minute, in particular between 2 and 4 tank volumes per minute.
Ink-jet printers are generally well known. Printers of this type have print heads having very small nozzles and passageways through which the ink is transported from a reservoir for application on to a substrate, for example, a sheet of paper, as a series of dots making up an image. A resolution of 400 dots per inch is not uncommon. The print head or the substrate to be printed is moved relative to one another to provide the desired application of ink to form the image.
US-A-5 121 131 describes a system and method of using a modified ink-jet printer to create transmissive images in a developed photographic film. The method described comprises selectively oxidizing portions of an opaque developed film with an oxidizing solution to form transmissive areas in the film. The oxidizing solution is highly concentrated and is applies to just those portions of the film in which a transmissive image is desired. In the regions where the oxidizing solution is applied, the silver grains are oxidized to form silver ions which are poor light absorbers. A computer-controlled ink-jet printer is used to direct very fine droplets of the oxidizing solution on to the film in the selected portions. A positive or negative image can be formed in this way. The resultant film requires no further processing and its surface is left substantially dry.